Three-dimensional package structure

ABSTRACT

A three-dimensional package structure includes an energy storage element, a semiconductor package body and a shielding layer. The semiconductor package body has a plurality of second conductive elements and at least one control device inside. The energy storage element is disposed on the semiconductor package body. The energy storage element including a magnetic body is electrically connected to the second conductive elements. The semiconductor package body or the energy storage element has a plurality of first conductive elements to be electrically connected to an outside device. The shielding layer is disposed between the control component and at least part of the magnetic body to inhibit or reduce EMI (Electro-Magnetic Interference) from the energy storage element and to get a tiny package structure. The three-dimensional package structure is applicable to a POL (Point of Load) converter.

RELATED APPLICATIONS

The present application is a divisional of U.S. application Ser. No.11/847,351 filed Aug. 30, 2007, and claims priority from, TaiwanApplication Number 096120840 filed Jun. 8, 2007, the disclosures ofwhich are hereby incorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a package structure, and moreparticularly to a three-dimensional package structure.

2. Description of the Prior Art

Increasing device complexity but shrinking size is common trend ofelectrical products. How to put more electrical elements or circuitsinto a limited space is important for electrical products' designers.Therefore, a three-dimensional package structure is a method to increasethe density of the electrical products.

Point-of-Load (POL) converter also can be called as DC/DC converter. Aconventional POL converter is packaged by BGA (Ball Grid Array) packageor LGA (Land Grid Array) package.

As shown in FIG. 1, a conventional POL converter 1 includes at least onecontrol device 11, at least one MOSFET 13 and a choke coil 15. Take BGApackage for example. The control device 11 and the MOSFET 13 and thechoke coil 15 are electrically connected to a substrate 17 havingelectrical circuits, such as printed circuit board, and then packaged tobe a POL converter package structure by molding technology.

In the conventional package structure, the control device 11, the MOSFET13, the choke coil 15, and other devices are disposed on the samehorizontal surface of the substrate 17. Therefore, the surface occupiedby the devices is pretty large. Moreover, packaging all devices on asingle package structure has several disadvantages. For example, onceany device inside the package structure is damaged, the whole packagestructure should be changed. Furthermore, during the operation of thechoke coil 15, electric and magnetic are generated which can interferewith the operation of the control device 11. This phenomenon is termedelectro-magnetic interference (EMI).

SUMMARY OF THE INVENTION

One object of the present invention is to provide a three-dimensionalpackage structure to solve the above-mentioned issues of theconventional package structure.

Another object of the present invention is to provide athree-dimensional package structure having a shielding layer to inhibitor reduce EMI.

Further another object of the present invention is to provide athree-dimensional package structure in which an energy storage elementis stacked on a semiconductor package body to reduce the size of thepackage structure.

Further another object of the present invention is to provide athree-dimensional package structure to improve the heat-dissipatingability.

Further another object of the present invention is to provide athree-dimensional package structure applicable to a POL converter inwhich devices except a choke coil are packaged inside a semiconductorpackage body and the choke coil is disposed on the semiconductor packagebody to be a three-dimensional package structure to reduce the size ofthe package structure.

In order to reach the above-mentioned purpose, according to oneembodiment of the present invention, the three-dimensional packagestructure includes a semiconductor package body, an energy storageelement and a shielding layer. The semiconductor package body has aplurality of second conductive elements and at least one control deviceinside. The energy storage element is disposed on the semiconductorpackage body and electrically connected to the second conductiveelements. The energy storage element has a magnetic body. The shieldinglayer is disposed between the control element and at least part of themagnetic body to inhibit or reduce EMI and to reduce the size of thepackage structure. The semiconductor package body or the energy storageelement has a plurality of first conductive elements to be electricallyconnected to an outside device. The three-dimensional package structureof the present invention is applicable to a DC/DC converter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional diagram illustrating a package structure ofa conventional POL converter.

FIG. 2 is a side view illustrating a three-dimensional semiconductorpackage structure according to an embodiment of the present invention.

FIG. 3A to FIG. 3D are cross-sectional diagrams illustrating severaltypes of structures of the second conductive elements and a shieldinglayer of the semiconductor structure according to the present invention.

FIG. 4A is a cross-sectional diagram illustrating a three-dimensionalpackage structure according to the present invention.

FIG. 4B is a diagram illustrating the structure inside anothersemiconductor package body.

FIG. 5 is a side view illustrating a three-dimensional semiconductorpackage structure according to another embodiment of the presentinvention.

FIGS. 6A to 6C are perspective diagrams illustrating the conductiveelements of the energy storage element according to thethree-dimensional package structure of FIG. 5.

FIGS. 7A to 7C are cross-sectional diagrams illustrating thethree-dimensional package structure of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

Some embodiments of the invention will now be described in greaterdetail. Nevertheless, it should be noted that the present invention canbe practiced in a wide range of other embodiments besides thoseexplicitly described, and the scope of the present invention isexpressly not limited except as specified in the accompanying claims.

As shown in FIG. 2, according to an embodiment of the present invention,a three-dimensional package structure 2 includes a semiconductor packagebody 21, an energy storage element 23 and a shielding layer 25. Thesemiconductor package body 21 has a first surface 213, a second surface211 opposite the first surface 213, and a sidewall 215 interconnectingthe first surface 213 and the second surface 211. The semiconductorpackage body 21 has a plurality of first conductive elements 216 on thesecond surface 211 or the sidewall 215 to be electrically connected toan outside device (not shown), such as a mother board. The firstconductive elements 216 can be, including but not limited to, leads,pads or solder balls. The semiconductor package body 21 further has aplurality of second conductive elements 217 to be electrically connectedto the energy storage element 23. The second conductive elements 217 canbe disposed on, but not limited to, the first surface 213. Thesemiconductor package body 21 can be such as, but not limited to, apackage body of QFN (Quad Flat No-lead) package, QFP (Quad FlatPackage), SSO (Shrink Small Outline) package, BGA (Ball Grid Array)package, and LGA (Land Grid Array) package. The semiconductor packagebody 21 further includes at least one control device 212 inside, such asa control chip (IC) or a driving chip (IC).

The energy storage element 23 is stacked on the first surface 213 of thesemiconductor package body 21. The energy storage element 23 iselectrically connected to the second conductive elements 217. In thisembodiment, the energy storage element 23 can be such as an inductorhaving a coil (not shown), a magnetic body 232, and a pair of electrodes231 electrically connected to the second conductive elements 217.Furthermore, the electrodes 231 can be formed directly by two ends ofthe coil or two leads connected to the two ends of the coil.

The shielding layer 25 is disposed between the control device 212 and atleast part of the magnetic body 232 to inhibit or reduce EMI from themagnetic body 232 on the control device 212. In this embodiment, theshielding layer 25 is disposed between the first surface 213 of thesemiconductor package body 21 and the energy storage element 23. Theshielding layer 25 can be a metal shielding layer such as a metal foil.The material of the shielding layer 25 can be one of copper, iron,nickel, aluminum. The shielding layer 25 can be fixed between the firstsurface 213 of the semiconductor package body 21 and the energy storageelement 23 by high heat-dissipating adhesive such as epoxy, silicon,silver adhesive, or conductive adhesive. Alternatively, a silveradhesive is directly coated between first surface 213 of thesemiconductor package body 21 and the energy storage element 23 to formthe shielding layer 25.

The following experiments are made on the package structure as is shownin FIG. 2. Suppose that the operation frequency of the control device212 is 200 kHz. When the shielding layer 25 is a copper foil, theoperation frequency of the control device 212 oscillates around 200 to300 kHz. When the shielding layer 25 is an aluminum foil, the operationfrequency of the control device 212 oscillates around 200 to 400 kHz.When there is no shielding layer 25 between the semiconductor packagebody 21 and the energy storage element 23, the operation frequency ofthe control device 212 oscillates around 200 to 600 kHz. According tothe above-mentioned experiments, during the operation of the controldevice 212, the magnetic body 231 will interfere the operation of thecontrol device 212 to make the operation frequency of the control device212 oscillate. By the disposition of the shielding layer 25, theoscillation range of the operation frequency of the control device 212will be reduced.

Furthermore, when the shielding layer 25 is a metal foil, there are twodisposition methods. First, during the molding process of thesemiconductor package body 21 and the energy storage element 23, theshielding layer 25 is disposed inside the semiconductor package body 21or the energy storage element 23 to make the shielding layer 25encapsulated inside the semiconductor package body 21 (as shown in FIG.3B) or inside the energy storage element 23 (as shown in FIG. 3C).Speaking in detail, as shown in FIG. 3B, if the shielding layer 25 isdisposed inside the semiconductor package body 21, when thesemiconductor package body 21 is electrically connected to the energystorage element 23, the shielding layer 25 can inhibit or reduce the EMIfrom the energy storage element 23 on the semiconductor package body 21,especially on the control device 212 inside the semiconductor packagebody 21. As shown in FIG. 3C, the shielding layer 25 is disposed insidethe energy storage element 23, when the energy storage element 23 iselectrically connected to the semiconductor package body 21, theshielding layer 25 can inhibit or reduce EMI from the energy storageelement 23 on the semiconductor package body 21, especially on thecontrol device 212 inside the semiconductor package body 21.

Secondly, the shielding layer 25 can be a part of lead frame 218 of thesemiconductor package body 21 or a part of lead frame of the energystorage element 23. As shown in FIG. 3D, during the design of the leadframe 218, a part of the lead frame 218 is in advance kept as theshielding layer 25. During the molding process, the part of the leadframe 218 is bended to between the control device 212 and at least partof the magnetic body 232, and then molding process is performed.Alternatively, a part of the lead frame (i.e., electrodes 231) of theenergy storage element 23 is bended to between the semiconductor packagebody 21 and the energy storage element 23 to become a shielding layer25, and then fixed by a high heat-dissipating adhesive on thesemiconductor package body 21 or the energy storage element 23.

The method for forming the second conductive elements 217 and the methodof the second conductive elements electrically connected to the energystorage element 23 will be described in detail as follows. As shown inFIG. 3A, the first conductive elements 216 are formed by the lead frame218 of the semiconductor package body 21 (as shown in FIG. 2). At thesame time, the leads 218 a remained in advance extend outside thesemiconductor package body 21. After the molding process on thesemiconductor package body 21 is completed, the leads 218 a is bendedalong the sidewall of the semiconductor package body 21 to the firstsurface 213 of the semiconductor package body 21 to form the secondconductive elements 217 a. Then, the electrodes 231 (such as leadsframe) of the energy storage element 23 are electrically connected andassembled to the second conductive elements 217 a by surface mountingtechnology. Alternatively, as shown in FIG. 3B, a plurality ofconductive structures 219 (such as copper pillars) are disposed on thelead frame 218 and extend toward the first surface 213 and are exposedoutside the first surface 213 to form the second conductive elements 217b. Then, the second conductive elements 217 b are electrically connectedto the electrodes 231 (such as lead frame) of the energy storage element23 by surface mounting technology. Moreover, as shown in FIG. 3C, theconductive structures 219 (such as copper pillars) disposed on the leadframe 218 extends toward the first surface 213 and are exposed outsidethe first surface 213 to form the second conductive elements 217 c.Then, the second conductive elements 217 are electrically connected tothe electrodes 231 of the energy storage element 23 by soldering method.

As shown in FIG. 4A and FIG. 4B, the three-dimensional package structure2 according to the present invention can be applicable to a POL(Point-of-Load) converter 3 which is also called as a DC/DC converter.The POL converter 3 includes a semiconductor package body 31 a (31 b),an energy storage element 33, and a shielding layer 35. The details ofthe corresponding structure relating to the energy storage element 33,the semiconductor package body 31 and the shielding layer 35 aredescribed as above-mentioned three-dimensional package structure 2including the energy storage element 23, the semiconductor package body31, and the shielding layer 25. They will not be described anymore.

The structure inside the semiconductor package body 31 a (31 b) and theenergy storage element 33 is shown in FIG. 4A. The semiconductor packagebody 31 a includes a lead frame 311, and a substrate 312, a plurality ofdevices (such as at least one control device 313, at least one MOSFET314, a resistor 315, and a capacitor 316), and a molding compound 318encapsulating the above-mentioned devices, as well as the connection ofbonding wires 319. The lead frame 311 is disposed inside a secondsurface (the second surface 211) of the semiconductor package body 31 a.The substrate 312 is mounted on a first surface 3111 of the lead frame311. Speaking in detail, the substrate 312 is mounted on the lead frame311 by adhesive (such as silver paste) or by soldering method. Thesubstrate 312 is a substrate having electrical circuits, such as a PCB(Printed Circuit Board), to increase electrical circuit density. A partof the devices of the POL inverter 3 can be mounted on the substrate 312and others can be mounted on the lead frame 311 to reduce the occupiedsurface of the lead frame 311 and to get a smaller surface of thesemiconductor package body 31 a. The devices on the substrate 312 can beelectrically connected to the electrical circuits of the substrate 312by bonding wires 319 or by flip-chip method. Then, the electricalcircuits of the substrate 312 are electrically connected to the leadframe 311 or the devices on the lead frame 311 by bonding wires 319. Thedevices on the lead frame 311 are electrically connected to the leadframe 311 by bonding wires 319 or flip-chip method. In this embodiment,a control device 313 and passive devices (such as a resistor 315 and acapacitor 316) are mounted on the substrate 312. The power devices (suchas at least one MOSFET 314) are disposed on the lead frame 311. Becausethe lead frame 311 has a heat-dissipating ability, the power devicesmounted on the lead frame can get a better heat-dissipating effect thanthose mounted on the substrate.

Furthermore, the device such as control device, power device, can beattached on the substrate or the lead frame by soldering method. Aftersoldering the device and before encapsulating the devices by the moldingcompound 318, an under-fill material (not shown) is injected into a gapbetween the device and the substrate 312 or the lead frame 311 andthereby extends solder joint life by limiting relative displacementbetween the device and the substrate or the lead frame during thermalcycling.

The energy storage element 33 can be a choke coil including electrodes331, a coil 332, and a magnetic body 333. The magnetic body 333encapsulates the coil 332. The electrodes 331 extend outside themagnetic body 333. The electrodes 331 can directly be formed by two endsof the coil 332 or by lead frame connected to two ends of the coil 332.

Alternatively, as shown in FIG. 4B, the structure inside thesemiconductor package body 31 b is disclosed herein. The semiconductorpackage body 31 b includes a lead frame 311, at least one control device313, at least one MOSFET 314, a resistor 315, and a capacitor 316, and amolding compound 318 encapsulating the above-mentioned devices, as wellas the connection of bonding wires 319. The control device 313, theMOSFET 314, the resistor 315, and the capacitor 316 are directly mountedon the lead frame 311. The control device 313, the MOSFET 314, theresistor 315, and the capacitor 316 are electrically connected to thelead frame 311 by bonding wires 319.

In order to accommodate the heat dissipation requirement, the energystorage element can be vertically stacked on the semiconductor packagebody or the semiconductor package body can be vertically stacked on theenergy storage element.

The following description describes another embodiment of the presentinvention. In the embodiment, a semiconductor package body is stacked onand electrically connected to an energy storage element and the energystorage element has a plurality of conductive elements to beelectrically connected to an outside device, such as a mother board.

As shown in FIG. 5, according to another embodiment of the presentinvention, a three-dimensional package structure 4 includes asemiconductor package body 41, an energy storage element 43 and ashielding layer 45. The semiconductor package body 41 has a firstsurface 411, a second surface 413 opposite the first surface 411, and asidewall 415 interconnecting the first surface 411 and the secondsurface 413. The semiconductor package body 41 has a plurality of secondconductive elements 416 on the first surface 411 or the sidewall 415 tobe electrically connected to the energy storage element 43. The secondconductive elements 416 can be such as leads, pads or solder balls. Thesemiconductor package body 41 can be such as a package body of QFN, QFP,SSO, BGA package, or LGA package. The semiconductor package body 41further includes at least one control device 412 inside, such as acontrol chip (IC) or a driving chip (IC).

In this embodiment, the energy storage element 43 can be such as aninductor having a coil (not shown), a magnetic body 432, and a pluralityof third conductive elements 431 to be electrically connected to thesecond conductive elements 416 of the semiconductor package body 41.Hence, the semiconductor package body 41 is stacked on and electricallyconnected to the third conductive elements 431 of the energy storageelement 43. The energy storage element 43 further has a plurality offirst conductive elements 433 used to be electrically connected to anoutside device, such as a mother board. The third conductive elements431 and the first conductive elements 433 can be leads of a lead frameinside the energy storage element 43. The lead frame can be alsoconnected to the two ends of the coil.

Furthermore, the shielding layer 45 is disposed between the controldevice 412 and at least part of the magnetic body 432 to inhibit orreduce EMI from the magnetic body 432 on the control device 412. In thisembodiment, the shielding layer 45 is disposed between the first surface411 of the semiconductor package body 41 and the energy storage element43. The shielding layer 45 can be a metal shielding layer such as ametal foil. The material of the shielding layer 45 can be copper, iron,nickel or aluminum. The shielding layer 45 can be fixed between thefirst surface 413 of the semiconductor package body 41 and the energystorage element 43 by high heat-dissipating adhesive such as epoxy,silicon, silver adhesive, or conductive adhesive. Alternatively, asilver adhesive is directly coated between the semiconductor packagebody 41 and the energy storage element 43 to form the shielding layer45.

Alternatively, in this embodiment, the shielding layer 45 can bedisposed inside the energy storage element 43 to make the shieldinglayer 45 encapsulated inside the energy storage element 43. (not shown)It can be manufactured by above-mentioned method, and will not bedescribed in detail anymore. Therefore, the shielding layer can inhibitor reduce the EMI from the energy storage element 43 on thesemiconductor package body 41, especially the control device 412 insidethe semiconductor package body 41.

FIGS. 6A to 6C are perspective diagrams illustrating the conductiveelements of the energy storage elements 43 a, 43 b, and 43 c accordingto another embodiment of the present invention. The energy storageelement 43 a, 43 b, 43 c with a third surface 435 and a fourth surface436 opposite the third surface 435 includes a plurality of firstconductive elements 433 and a plurality of third conductive elements431. The first conductive elements 433 and the third conductive elements431 are leads of at least one lead frame inside the energy storageelement. As shown in FIG. 6A, the first conductive elements 433 and thethird conductive elements 431 extend out of the energy storage element43 a from its sidewall. The first conductive elements 433 are bended tothe third surface 435 to be electrically connected to the outsidedevice. The third conductive elements 431 are bended to the fourthsurface 436 to be electrically connected to the semiconductor packagebody. As shown in FIG. 6B, the first conductive elements 433 extend fromthe third surface 435 to the fourth surface 436. As shown in FIG. 6C,the first conductive elements 433 and the third conductive elements areextended out of the energy storage element from the same sidewall, andthe first conductive elements 433 are bended to the third surface 435 tobe electrically connected to the outside device, and the thirdconductive elements 431 are bended to the fourth surface to beelectrically connected to the semiconductor package body.

As shown in FIGS. 7A to 7C, the three-dimensional package structure 4according to the present invention can be applicable to a POL converter,which is also called as a DC/DC converter. As shown in FIG. 7A, thesemiconductor package body 31 c, similar to the semiconductor packagebody 31 a, includes a lead frame 311, and a substrate 312 and aplurality of devices (such as at least one control device 313, at leastone MOSFET 314, a resistor 315, and a capacitor 316). The substrate 312with electrical circuits can be a multi-layer PCB having a metal layerfor serving as the shielding layer. Alternatively, a first surface ofthe control device 313 is flip-chipped on and electrically connected tothe substrate 312, and a second surface of the control device 313opposite the first surface of the control device 313 has a metal layerthereon for serving as the shielding layer.

As shown in FIG. 7B, the semiconductor package body 31 d, similar to thesemiconductor package body 31 b, includes a lead frame 311, at least onecontrol device 313, at least one MOSFET 314, a resistor 315, and acapacitor 316. The above-mentioned elements, as well as the connectionof bonding wires 319, are protected by a molding compound 318. Thedetailed structures inside the semiconductor package bodies 31 c, 31 dwill not be described again.

In this embodiment, as shown in FIG. 7C, a semiconductor package body 31e is disclosed herein. The semiconductor package body 31 e includes asubstrate 310 with devices mounted thereon. The substrate 310 withelectrical circuits is such as a PCB. The devices include at least onecontrol device 313, at least one MOSFET 314, resistor 315, and capacitor316. The MOSFET 314, as well as the connection of thin wires 317, isprotected by a seal layer G′. The control device 313, the resistor 315,and the capacitor 316, and the seal layer G′ is protected by an outerseal layer G. The semiconductor package body 31 e is electricallyconnected to the energy storage element 43.

In the present invention, the three-dimensional package structureassembled by vertical stacking can solve the problem of the conventionalpackage structure having all devices on the same horizontal surface toget a tinier package structure. Furthermore, the substrate withelectrical circuits inside the semiconductor package body has anadvantage of high electrical-circuit density. Therefore, it is allowableto have high density circuit design inside a tiny volume to meet therequirement of miniaturization.

The three-dimensional package structures according to the presentinvention are applicable to a POL converter. Except the choke coil, thedevices are all packaged inside a semiconductor package body. Then, thechoke coil is vertically connected to the semiconductor package body toform a three-dimensional package structure to get a tiny packagestructure.

In the present invention, the choke coil and the semiconductor packagebody are two independent elements. It can meet different users' requestson electricity and package size. Therefore, it is easy for users to makemost appropriate combination and arrangement and to add variety and toreduce the risk of slow moving item and to increase flexibility.Compared to the conventional package structure, all devices are moldedinside a single package structure. Once any one device is damaged, thepackage structure should be changed. Therefore, it will cause the wasteof materials.

Although specific embodiments have been illustrated and described, itwill be appreciated by those skilled in the art that variousmodifications may be made without departing from the scope of thepresent invention, which is intended to be limited solely by theappended claims.

1. A three-dimensional package structure, comprising: an energy storageelement having a protruded metal electrode which has a flat metalportion; a semiconductor package body having a bottom electrode; and ametal pillar, electrically couples said metal electrode to said bottomelectrode.
 2. The three-dimensional package structure according to claim1, wherein said metal pillar having a top surface coplanar to a topsurface of said semiconductor body; and said top surface of said metalpillar touches a bottom surface of said flat metal portion of saidprotruded metal electrode.
 3. The three-dimensional package structureaccording to claim 1, wherein said metal pillar having a top surfaceprotruded above a top surface of said semiconductor body.
 4. Thethree-dimensional package structure according to claim 1, furthercomprising a shielding layer, embedded in said semiconductor packagebody.
 5. The three-dimensional package structure according to claim 4,wherein said shielding layer is a metal portion extended from said metalpillar.
 6. The three-dimensional package structure according to claim 1,further comprising a shielding layer, embedded in said energy storageelement.
 7. The three-dimensional package structure according to claim6, wherein said shielding layer is selected from a group consisted ofcopper, iron, nickel, and aluminum.
 8. The three-dimensional packagestructure according to claim 1, wherein said bottom electrode is part ofa lead frame.
 9. The three-dimensional package structure according toclaim 1, wherein said semiconductor package body is selected from agroup consisted of QFN (Quad Flat No-lead) package, QFP (Quad FlatPackage), SSO (Shrink Small Outline) package, BGA (Ball-Grid Array)package or LGA (Land-Grid Array) package.